Use 5–12% extra space with caps, but not with lowercase

Let­terspac­ing (also known as char­ac­ter spac­ing or track­ing) is the adjust­ment of the hor­i­zon­tal white space between the let­ters in a block of text. Unlike kerning, which affects only des­ig­nated pairs of let­ters, let­terspac­ing affects every pair.

Low­er­case let­ters don’t ordi­nar­ily need let­terspac­ing.

Cap­i­tal let­ters usu­ally appear at the begin­ning of a word or sen­tence, so they’re designed to fit cor­rectly next to low­er­case let­ters. But when you use cap­i­tal let­ters together, that spac­ing is too tight. That’s why you should add 5–12% extra let­terspac­ing to text in all caps or small caps. This is par­tic­u­larly impor­tant at small sizes (e.g., the footer of a court fil­ing).